Redox-active monolayers and bistable molecules for...

Florence DuclairoirIndo-French Workshop – 06-10/10/2008

Redox-active monolayers and bistablemolecules for molecular memories

applicationsFlorence Duclairoir, Lionel Dubois, Pascale Maldivi, CEA-Grenoble –

Institut Nanosciences et CryogénieLaboratoire de Chimie Inorganique et Biologique (UMR-E 3 CEA-UJF)

Tiziana Pro, Julien Buckley, Eric Jalaguier, Barbara De Salvo, CEA-Grenoble-LETI, Département des Nanotechnologies

Kai Huang, Régis Barattin, Guillaume Delapierre, CEA-Grenoble-LETI, Département des Microtechnologies pour la Biologie et la Santé

Florence Duclairoir - Direction des Sciences de la MatièreIndo-French Workshop – 06-10/10/2008


Introduction

ChannelSource Drain

Oxide

VDVS

Metal

VG

ChannelSource Drain

Oxide

VDVS

Metal

VG

Erased Written

state « 0 » state «1 »

Writing/Erasingoperations

VG >>> 0 V

Non-volatile memory

ID

VGVT0 VT1

ΔVT Charges in the floating gate induce

a shift of VT

The two states are defined by the

presence/absence ofelectrons in the FG

floating gate


Introduction

ChannelSource Drain

Oxide

VDVS

Metal

VG

ITRS for Non-volatile memory

6.786-78-96-78-9Tunnel oxide EOT (nm)

224565Technology Node (nm)Year

NANDNORNANDNORNANDNOR

9-106-810-138-1010-1310-12Interpoly oxide EOT (nm)

4.5/2.314-174.5/2.312-154.511-14

201620102007

Cell size (λ²)

Solutions exist Solutions known Solutions NOT known


Introduction

ChannelSource Drain

Oxide

VDVS

Metal

VG

6.786-78-96-78-9Tunnel oxide EOT (nm)

224565Technology Node (nm)

Year

NANDNORNANDNORNANDNOR

9-106-810-138-1010-1310-12Interpoly oxide EOT (nm)

4.5/2.314-174.5/2.312-154.511-14

201620102007

Cell size (λ²)

Solutions exist Solutions known Solutions NOT known

Miniaturization problems

Charge leakage


Research paths investigated

Standard non-volatile memory

Pushing the scaling limits of current technologies

Source: LETI - D2NTJ. Buckley, B. De Salvo

New transistor

structuresNew

Materials

Development of new technologies:

Molecular memories

Introduction


resistive switchingmemories

Molecular memory devices

capacitive devices

Flash-likeapproach

- North Carolina State Uni - NASA Ames Research Center

DRAM-likeapproach

- ZettaCore

Crossbararchitecture

- Caltech - HP - Infineon/Qimonda

Literature examples

Introduction Source: LETI - D2NTJ. Buckley, B. De Salvo


p+ p+n-SiSource Drain

electrolyte

SiO2

S. Gowda et al, IEDM 2004.

Id-Vg hysterisis

Flash-like approach

Introduction


R. Shrivastava (Zettacore), Stanford Computer Systems Colloquium, 2005.

High capacitance of molecules allows shallow trench capacitor

DRAM approach (ZettaCore)

Introduction


Cur

rent

Voltage

Cell switchingcharacteristic

In R switching device, memory cell I-V has hysteris

Memory Cell

R-switching approach

Introduction

Crossbar architecture


Molecules specifications



capacitive devices

Redox active molecule

Redox bistablemolecule

With Tethersubstituent

Introduction


The research axes

Redox active molecules

Redox bistablemolecule

Design of the molecules depends on the grafting technique used

« simple » synthesis steps

Development of grafting procedures

Design of the molecule depends on the targeted motion of the molecule

complex synthesis steps

extensive characterization required

Grafting procedure developed only once the bistability is confirmed

1-redox monolayer development 2-Molecular machine synthesis

Introduction


Multi-disciplinary project

Si

10 µmSiO2PECVD

Si

Molecular Chemistry Surface Chemistry

Surface functionalization

Molecular design, synthesis, theoritical

studies

Si technology

Devices fabrication, Electrical measurements,

simulation

Redox monolayer


Choice of molecules



capacitive devices

Flash-likeapproach

DRAM-likeapproach

Source: LETI - D2NT

N

N

N

S N

N

N

SFe2+

OO

Redox monolayer

porphyrin ferrocene

viologen

polyoxometallates


Different grafting routes


Si

Redox monolayer

● Electrostatic- SAM+/Ms-

● Electrochemical- Diazonium- Doping entrapment

into PPy

● Chemical- Hydrosilylation- Click chemistry

….

H

Si

OH

Si


Choice of the grafting process

Indirect grafting on Si

bi-functionalised spacer


Molecular design, synthesis

Si

grafting on Si

Si-C bond between the molecule and the susbtrate

Hydrosilylation reaction

spacer with terminal insaturation

Click-chemistry reaction

spacer with terminal azide function

Redox monolayer


Indirect grafting

1st step: Spacer grafting

Hydrosilylation reaction

2nde step: Triazole formation

Cycloaddition

Clic reaction

Patent: G. Delapierre, F. Duclairoir, JC. Marchon, PCT/FR2006/002395

Si SiH H

Si Si Si

NN3

Nn n

n

N

N

redox molecule

redox molecule

N

N

N3

n

Redox monolayer


Immobilisation of the spacer

H

Si

1

Si

Cl

2

→ Successful grafting of the spacer

Cl 2p

202 eV 200.6 eV

XPS dataC-H vibrations region

2750 2850 2950 3050

No C-H signal for the

Si hydride surface.

νs et νas of C-H at 2852 et 2923 cm-1

IR data

K. Huang

Redox monolayer


IR data

2000 2100 2200

New band at 2100 cm-1

for the vibration of the N3function.

Si-H and N3 vibrations region

Substitution reaction on the surface

Si

Cl

2

Si

N3

3

→ Successful Cl→N3 substitution

XPS data

N 1s405 eV

401 eV

K. Huang

Redox monolayer


Coupling reaction on the surface

Si

N3

3 4

→ successful grafting of the redox molecule

2000 2100 2200

IR data

Disappearance of the band at

2100 cm-1

DTBS

XPS data

Zn 2p1023 eV

1046 eV

K. Huang

Si

N

N

N

redoxmolecule

Redox monolayer


-1,00E-04

-5,00E-05

0,00E+00

5,00E-05

1,00E-04

1,50E-04

-0,4 -0,2 0 0,2 0,4 0,6 0,8 1 1,2

Voltage (V)

Cur

rent

(A)

Ethynyl ferrocene in solution

electrolyte Bu4NPF6 1M in PCreference electrode = Pt, counter-electrode = Pt

Eredox = 0.43 V

Fc → Fc+

E’redox = 0.41 V

Ethynyl ferrocene immobilised on Siworking electrode = functionnalized Si substrateworking electrode = Pt

Redox behavior is reproducedK. HuangR. Barattin

Electrochemical characterization

Redox monolayer ● Chemical grafting


K. HuangR. Barattin


Redox monolayer ● Chemical grafting

-3,00E-05

-2,00E-05

-1,00E-05

0,00E+00

1,00E-05

2,00E-05

3,00E-05

4,00E-05

5,00E-05

-0,1 0,1 0,3 0,5 0,7 0,9 1,1 1,3 1,5

Voltage (V)

Cur

rent

(A)

E1redox = 0.55 V

E2redox = 0.875 V

ΔE = E1 – E2 = 0.32 V

Zn-P in solution

P → P+.

P+. → P++

working electrode = functionalized Si substrateworking electrode = Pt

Zn-P immobilised on Si

E1’redox = 0.64 V

E2’redox = 1.01 V

ΔE = E1’ – E2’ = 0.37 V


Redox behavior is reproduced


Redox monolayer ● Electrochemical grafting

SiH

Si

N+

N+

-1,6 -1,4 -1,2 -1,0 -0,8 -0,6 -0,4 -0,2 0,0Potentiel (V)

5 μA

En BàGWE: modified Si n+RE: Ag/Ag+CE: PtNBu4 BF4CH3CN dist20 mV/s

E1 = - 0.70 VE2 = - 1.10 V


molecules

Si

Images SEM

Si substrate(p-type, 7-10 Ω*cm)

Capacitive cell Pseudo-MOS cell

use of a box SOI etched in order to

obtain « dices » of Si

T. ProJ. Buckley

Si nanowire cell

The Si nanowires are obtained by lithography

techniques

S D

SiO2PECVD

SiO2 thermique

Hybrid devices under development

Redox monolayer


Freq: 100 Hz,

Scan window: 1.5 V /0.5 V

N2 atmosphere

Ag tip

solvionic electrolyte

C-V

1 0.5 0 0.5 10

1 .10 4

2 .10 4

3 .10 4

4 .10 4

5 .10 4

6 .10 4

5.795 10 4−×

1.993 10 5−×

Mes16 1⟨ ⟩

A3

Mes16 2⟨ ⟩

A3

Oct 1⟨ ⟩

A3

Oct 2⟨ ⟩

A3

1.11.1− Mes16 0⟨ ⟩ Mes16 0⟨ ⟩, Oct 0⟨ ⟩, Oct 0⟨ ⟩,V

Farads/cm2

--- Ferrocene (redox active)

--- 1-octadecene (redox inactive)

1

4

23

150x 300 µm2 area

Si

Fe

Direct grafting(no linker, nooxide layer)

Redox monolayer

Charges are exchangedbetween the redox centre and

the Si surface

Functionalized capacitive cell

T. ProJ. Buckley


Redox monolayer

Work on progress

Test a number of redox molecules

Study the impact of the spacer length

Study the impact of the conjugation of the spacer

Theoretical calculations and simulations to provide a model that will help understanding the charges transfer between the redox centre and the surface

Test the other cells that are totally « solid »


Choice of molecules



capacitive devices

Source: LETI - D2NTBistable molecule

Target: production of a redox bistable molecule with a porphyrinic core

Reach higher retention time


Bistable molecule

NN

NH

HN

OO

(CH2)n

OO

OO

O O

C H2)n(

J-C MarchonThèse A. Castaings

ZnBCP-8 αααα(Zn-N = 2,05 Å)

Closed form

NiBCP-8 αβαβ(Ni-N = 1,95 Å)

Open formwith n = 8

1st generation of bridled chiroporphyrins


8.858.908.959.009.05

8 .48 .68 .89 .0

αααα majoritaire

Closed form

αβαβ

Open form

β-pyrrole 1H NMR β-pyrrole 1H NMR

X-ray structure

X-ray structure

NiBCP-8Bistable molecule

Thèse A. Castaings

ZnBCP-8

MBCP-8 characterization

+ECD

αααα

-ECD

αβαβ


Bistable molecule

NN

NH

HN

OO

(CH2)n

OO

OO

O O

C H2)n(

Thèse A. Castaings

What about M = Mn?

MnII – “big”

Closed form

MnIII – “small”

Open form

Eox

Ered

?

with n = 8 and M = Mn ?


Bistable molecule

Conformational change induced by an electron transfer

MnII/IIIBCP-8

MnBCP-n conformations

Thèse A. Castaings

αααα form

+ e-

- e-+Mn(III) Mn(III)

αααα formαααα form

MnII/IIIBCP-12

Mn(II)

+ e-

- e-Mn(III)

αβαβ form αααα form

Mn(II)


Bistable molecule

Next generation of bridled chiroporphyrin

NN

NH

HN

OO

(CH2)n

OO

OO

O O

CH2)n(

Thèse A. Fateeva

1st generation of BCP:

Only one enantiomer is available

New generation:

Studies possible on 2 enantiomersModification of the steric parameters


Bistable molecule

Work planned or on progress

NMR studies (2D, T°C dependence)→ Attribution of conformations

CD studies → correlation between the CD sign and the conformation?

Electrochemistry studies→ Electrochemical behavior of all these species→ Redox bistability?


SPRAMMartial BillonSCIBBenoit Fleury (postdoc)Florence DuclairoirLionel DuboisAlexandra Fateeva (PhD)Pascal MaldiviAdrian Calborean (PhD)Anabarasan KalaiselvanGérard BidanJean-Claude Marchon

DTBSGuillaume DelapierreRegis Barattin (postdoc)Kai Huang (postdoc)Nicoleta Joo (PhD)D2NTBarbara De SalvoEric JalaguierJulien BuckleyTiziana Pro (PhD)

Lab. ChimieInorganique& MatériauxMoléculaires

Synthesis and/or graftingAtomistic

Synthesis and/or graftingAtomistic

GraftingSi technology

GraftingSi technology

O. Renault (XPS)E. Martinez (XPS)N. Rochat (MIR)

C. Licitra (MIR, ellipso)D. Mariolle (AFM)

Acknowledgment


Fundings

Programme CEA Chimtronique

EST Marie Curie « Chemtronics »

ANR MEMO


Thank you for your attention


Bistable molecule

NN

N

N

M

OO

(CH2)n

OO

OO

O O

n(H2C)

Hypothetic bistability?

Incorporation in a device

No bistability Ref: Misra, IEEE, 2004

Fe

O

OHOH

Incorporation in a device

What next?

Evaluation of the new molecular motors

Redox-active monolayers and bistable molecules for...

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